1. Field of Invention
The present invention relates to a monitoring system composed of plural cameras that can adjust a shooting area through pan, tilt, and zooming control, and so on, and especially relates to a monitoring system that shoots with resolution according to distribution of importance for monitoring, while allowing shooting an entire area subject to monitoring at the same time.
2. Description of the Related Art
In recent years, research and development have been actively taking place for a monitoring system using plural cameras, mainly targeting for surveillance as an intended purpose. For monitoring with plural cameras, two requirements must be satisfied: (Requirement 1) to reduce areas, which become a blind spot, as much as possible, in an area subject to monitoring (an area targeted for monitoring), and (Requirement 2) to acquire as much detailed shooting information as possible for an important area within the monitoring area.
Among conventional devices using plural cameras, there is a mobile object detection deciding device, as a representative conventional device shown in patent literature 1, that uses a combination of a camera for shooting a wide range area and a camera for shooting a narrow range area in detail, which achieves above Requirements 1 and 2.
FIG. 1 is a diagram that shows a configuration of the mobile object detection deciding device of patent literature 1, in which (i) a detecting camera device 9010 shoots a detection object in a wider shooting range with a camera 9011 and a reflecting mirror 9012, (ii) a mobile object extracting unit 9013 extracts the detection object from a shot image, and (iii) a location information extracting unit 9014 obtains location information subject to detection in a wide detection area by extracting location information of the detection object. Also, a decision camera device 9020 obtains detailed information of the detection object by having a camera controlling unit 9022 control a rotation angle, a depression angle, and a zooming ratio of camera 9021 based on the location information of the detection object and shooting an enlarged image of the detection object. In this way, patent literature 1 discloses that a blind spot is eliminated by positioning the detecting camera device 9010, which simultaneously shoots all directions, in a manner such as in which hexagons showing its detection range are located next to each other, as shown in FIG. 2, and the decision camera device 9020 is controlled based on a location of the detection object detected by the detecting camera device 9010.
In addition, patent literature 2 aims at shooting a continuous wide range area such as a panoramic image (above Requirement 1) and discloses having a redundant part in a shooting area located next each other by using plural cameras that can control a convergence angle, and controlling the convergence angle of the cameras to keep the redundant area in a certain range. FIG. 3 is a drawing that shows a configuration of an imaging device described in patent literature 2. In FIG. 3, plural cameras, 2003a and 2003b, which shoot an object 2001, can shoot a wide range of area such as a panoramic image without creating a blind area between shooting areas of the plural number of cameras, by controlling a convergence angle for keeping a redundant area in a shooting range between cameras in a certain area with using shooting information from a plurality of pieces of image information obtained from the plural number of cameras, 2003a and 2003b through a convergence angle controlling unit 2021 that provides a discretional convergence angle to the plural number of cameras and imaging ratio information made available in advance in an optical parameter storage unit 2023.
Furthermore, using plural cameras that have a camera platform and a zooming control, patent literature 3 discloses that a camera, which zooms in to track some incursion object, transmits a request for scaling up a view to a camera that monitors an adjacent area, and further discloses that the camera receiving the request for scaling up the view controls to include an area normally covered by the camera tracking the object and an area normally covered by the self camera, so as to satisfy the above Requirement 1 and Requirement 2. FIG. 4 is a diagram that shows a configuration of an incursion object monitoring device described in patent literature 3. The incursion object monitoring device in patent literature 3 includes plural incursion object monitoring devices that switch between three types of shooting modes: a “normal” mode for monitoring a prescribed area, a “tracking” mode for tracking and shooting a incursion object, and a “wide-angle” mode for shooting an area assigned to a camera located next by extending a field angle. When an incursion object monitoring device among the plural incursion object monitoring devices set in the “normal” mode detects an incursion object through a process of differences in an image signal, it switches the mode from the “normal” mode to the “tracking” mode, and tracks the incursion object and shoots it in detail by controlling a zoom lens 3102 and controlling a platform of a camera 3101 through a camera platform controlling device 3105 and a zoom controlling device 3116 based on the information of the incursion object. Furthermore, through transmission of a view scale up request to other incursion object monitoring device that monitors other monitoring area next to the monitoring area where the incursion object is being tracked, an incursion object monitoring system that has received the request switches the mode from the “normal” mode to a “scale up” mode, controls the zoom lens 3102 and scales up a view of its monitoring range.
In this way, as shown in FIG. 5, when an incursion object 3610 appears at a location shown in FIG. 6 when a first incursion object monitoring device 3601 monitors a monitoring area 3603 and a second incursion object monitoring device 3602 monitors a monitoring area 3604, it seems that the second incursion object monitoring device 3602 can only monitor a part of the monitoring area 3604 and a blind spot is generated because its mode is switched to the “tracking” mode. However, by expanding the monitoring area 3603 of the first incursion object monitoring device 3601 (expanded monitoring area 3608) in the “wide-angle” mode, it covers the situation where the blind spot of second incursion object monitoring device 3602 is generated.
Additionally, in patent literature 4, a configuration is disclosed for the case where plural areas are divided and monitored by a set of camera, a direction and zooming of a camera corresponding to the plural of areas are preset, and plural presets for plural cameras are centrally controlled from a terminal. FIG. 7 is a diagram to show a configuration of a terminal camera unit described in patent literature 4. In FIG. 7, both of a TV camera 4021 and a lens unit 4022 of the terminal camera unit are controlled based on a command from a terminal controlling unit 4023 and an image signal is output. The terminal controlling unit 4023 makes the TV camera 4021 rotate in horizontal and vertical directions by providing a rotation command to a rotation unit 4024 that retains the TV camera 4021. Also, a preset unit 4025 belongs to the terminal controlling unit 4023, which memorizes plural pieces of combined information on directions of TV camera 4021 (horizontal and vertical directions) and functions (zooming and focusing) of the lens unit 4022 as rotation information and lens setup information, and automatically adjusts a direction of the TV camera 4021 view and a zooming value to designated values by certain rotation information and lens setup information designated through a controlling command from an external entity.
Also, FIG. 8 shows a configuration example of a monitoring system using the terminal camera unit illustrated in FIG. 7. In FIG. 8, a terminal camera units 4111, 4112, 4113, . . . are connected in parallel with a personal computer 4031 through a pair of transmission lines, which are a common monitoring line 4015 and a command line 4016, and the personal computer 4031 selects a discretional terminal camera unit from the plural terminal camera units, and centrally controls the terminal cameras 4111, 4112, 4113, . . . based on rotation information and lens setup information memorized in a preset unit. In this way, a user can easily zoom and monitor an area he wants to look at by selecting a preset necessary for a required camera.    Patent Reference 1: Patent Publication No. 3043925 (Pages 8 & 10, FIG. 1);    Patent Reference 2: Japanese Laid-Open Patent No. 7-303207 (Page 5, FIG. 1);    Patent Reference 3: Japanese Laid-Open Patent No. 2001-245284 (Pages 11, 12 and 17, FIGS. 1, 16 and 17); and    Patent Reference 4: Japanese Laid-Open Patent No. 10-229511 (Page 6, FIG. 3).